Many Innerkids experience Ageplay on a very real emotional level, as real and visceral as does a Biokid. For them, the activities and events of Ageplay aren't mere Roleplay, but are very real on the most powerful levels.
But that's focusing just on the physical, the external, where (indeed) an adult who is behaving like a child, but isn't a child, can be thought of as playing a role.
But hereabouts, we care only about the Inner Journey, not the merely external -- so many Innerkids, who practice Emotionally Real Adult Ageplay, are experiencing the feelings and sensitivities which she did at that biological age.
For her, the play, the activities of Adult Ageplay, are a role only in the most superficial sense -- the real *point* to all of that play, and of appearing to take on a role, is the trust and comfort she needs to re-experience the very *real* thoughts and feelings which she did back then, when she was biologically her Innerkid's age.
For her, being in that place is *not* a role -- her Innergirl is simply *her* (in all the most important ways), when she *was* that age.
The motivation for that varies, but the point is to make this Inner Journey *real*, emotionally real, for many Adult Ageplayers.
That's Realplay, as opposed to Roleplay.